2 * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
3 * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
4 * Copyright 2011-2012, cozybit Inc.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include "ieee80211_i.h"
13 #include "driver-ops.h"
15 #ifdef CONFIG_MAC80211_VERBOSE_MESH_SYNC_DEBUG
16 #define msync_dbg(fmt, args...) \
17 printk(KERN_DEBUG "Mesh sync (%s): " fmt "\n", sdata->name, ##args)
19 #define msync_dbg(fmt, args...) do { (void)(0); } while (0)
22 /* This is not in the standard. It represents a tolerable tbtt drift below
23 * which we do no TSF adjustment.
25 #define TOFFSET_MINIMUM_ADJUSTMENT 10
27 /* This is not in the standard. It is a margin added to the
28 * Toffset setpoint to mitigate TSF overcorrection
29 * introduced by TSF adjustment latency.
31 #define TOFFSET_SET_MARGIN 20
33 /* This is not in the standard. It represents the maximum Toffset jump above
34 * which we'll invalidate the Toffset setpoint and choose a new setpoint. This
35 * could be, for instance, in case a neighbor is restarted and its TSF counter
38 #define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
42 struct ieee80211_mesh_sync_ops ops
;
46 * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
48 * @ie: information elements of a management frame from the mesh peer
50 static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems
*ie
)
52 return (ie
->mesh_config
->meshconf_cap
&
53 MESHCONF_CAPAB_TBTT_ADJUSTING
) != 0;
56 void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data
*sdata
)
58 struct ieee80211_local
*local
= sdata
->local
;
59 struct ieee80211_if_mesh
*ifmsh
= &sdata
->u
.mesh
;
60 /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
61 u64 beacon_int_fraction
= sdata
->vif
.bss_conf
.beacon_int
* 1024 / 2500;
65 spin_lock_bh(&ifmsh
->sync_offset_lock
);
67 if (ifmsh
->sync_offset_clockdrift_max
< beacon_int_fraction
) {
68 msync_dbg("TBTT : max clockdrift=%lld; adjusting",
69 (long long) ifmsh
->sync_offset_clockdrift_max
);
70 tsfdelta
= -ifmsh
->sync_offset_clockdrift_max
;
71 ifmsh
->sync_offset_clockdrift_max
= 0;
73 msync_dbg("TBTT : max clockdrift=%lld; adjusting by %llu",
74 (long long) ifmsh
->sync_offset_clockdrift_max
,
75 (unsigned long long) beacon_int_fraction
);
76 tsfdelta
= -beacon_int_fraction
;
77 ifmsh
->sync_offset_clockdrift_max
-= beacon_int_fraction
;
80 tsf
= drv_get_tsf(local
, sdata
);
82 drv_set_tsf(local
, sdata
, tsf
+ tsfdelta
);
83 spin_unlock_bh(&ifmsh
->sync_offset_lock
);
86 static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data
*sdata
,
88 struct ieee80211_mgmt
*mgmt
,
89 struct ieee802_11_elems
*elems
,
90 struct ieee80211_rx_status
*rx_status
)
92 struct ieee80211_if_mesh
*ifmsh
= &sdata
->u
.mesh
;
93 struct ieee80211_local
*local
= sdata
->local
;
97 WARN_ON(ifmsh
->mesh_sp_id
!= IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET
);
99 /* standard mentions only beacons */
100 if (stype
!= IEEE80211_STYPE_BEACON
)
103 /* The current tsf is a first approximation for the timestamp
104 * for the received beacon. Further down we try to get a
105 * better value from the rx_status->mactime field if
106 * available. Also we have to call drv_get_tsf() before
107 * entering the rcu-read section.*/
108 t_r
= drv_get_tsf(local
, sdata
);
111 sta
= sta_info_get(sdata
, mgmt
->sa
);
115 /* check offset sync conditions (13.13.2.2.1)
118 * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
121 if (elems
->mesh_config
&& mesh_peer_tbtt_adjusting(elems
)) {
122 clear_sta_flag(sta
, WLAN_STA_TOFFSET_KNOWN
);
123 msync_dbg("STA %pM : is adjusting TBTT", sta
->sta
.addr
);
127 if (rx_status
->flag
& RX_FLAG_MACTIME_MPDU
&& rx_status
->mactime
) {
129 * The mactime is defined as the time the first data symbol
130 * of the frame hits the PHY, and the timestamp of the beacon
131 * is defined as "the time that the data symbol containing the
132 * first bit of the timestamp is transmitted to the PHY plus
133 * the transmitting STA's delays through its local PHY from the
134 * MAC-PHY interface to its interface with the WM" (802.11
137 * T_r, in 13.13.2.2.2, is just defined as "the frame reception
138 * time" but we unless we interpret that time to be the same
139 * time of the beacon timestamp, the offset calculation will be
140 * off. Below we adjust t_r to be "the time at which the first
141 * symbol of the timestamp element in the beacon is received".
142 * This correction depends on the rate.
144 * Based on similar code in ibss.c
148 if (rx_status
->flag
& RX_FLAG_HT
) {
150 * In principle there could be HT-beacons (Dual Beacon
151 * HT Operation options), but for now ignore them and
152 * just use the primary (i.e. non-HT) beacons for
157 rate
= local
->hw
.wiphy
->bands
[rx_status
->band
]->
158 bitrates
[rx_status
->rate_idx
].bitrate
;
160 /* 24 bytes of header * 8 bits/byte *
161 * 10*(100 Kbps)/Mbps / rate (100 Kbps)*/
162 t_r
= rx_status
->mactime
+ (24 * 8 * 10 / rate
);
165 /* Timing offset calculation (see 13.13.2.2.2) */
166 t_t
= le64_to_cpu(mgmt
->u
.beacon
.timestamp
);
167 sta
->t_offset
= t_t
- t_r
;
169 if (test_sta_flag(sta
, WLAN_STA_TOFFSET_KNOWN
)) {
170 s64 t_clockdrift
= sta
->t_offset_setpoint
172 msync_dbg("STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld",
174 (long long) sta
->t_offset
,
176 sta
->t_offset_setpoint
,
177 (long long) t_clockdrift
);
179 if (t_clockdrift
> TOFFSET_MAXIMUM_ADJUSTMENT
||
180 t_clockdrift
< -TOFFSET_MAXIMUM_ADJUSTMENT
) {
181 msync_dbg("STA %pM : t_clockdrift=%lld too large, setpoint reset",
183 (long long) t_clockdrift
);
184 clear_sta_flag(sta
, WLAN_STA_TOFFSET_KNOWN
);
190 spin_lock_bh(&ifmsh
->sync_offset_lock
);
192 ifmsh
->sync_offset_clockdrift_max
)
193 ifmsh
->sync_offset_clockdrift_max
195 spin_unlock_bh(&ifmsh
->sync_offset_lock
);
198 sta
->t_offset_setpoint
= sta
->t_offset
- TOFFSET_SET_MARGIN
;
199 set_sta_flag(sta
, WLAN_STA_TOFFSET_KNOWN
);
200 msync_dbg("STA %pM : offset was invalid, "
201 " sta->t_offset=%lld",
203 (long long) sta
->t_offset
);
212 static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data
*sdata
)
214 struct ieee80211_if_mesh
*ifmsh
= &sdata
->u
.mesh
;
216 WARN_ON(ifmsh
->mesh_sp_id
217 != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET
);
218 BUG_ON(!rcu_read_lock_held());
220 spin_lock_bh(&ifmsh
->sync_offset_lock
);
222 if (ifmsh
->sync_offset_clockdrift_max
>
223 TOFFSET_MINIMUM_ADJUSTMENT
) {
224 /* Since ajusting the tsf here would
225 * require a possibly blocking call
226 * to the driver tsf setter, we punt
227 * the tsf adjustment to the mesh tasklet
229 msync_dbg("TBTT : kicking off TBTT "
231 "clockdrift_max=%lld",
232 ifmsh
->sync_offset_clockdrift_max
);
233 set_bit(MESH_WORK_DRIFT_ADJUST
,
236 msync_dbg("TBTT : max clockdrift=%lld; "
237 "too small to adjust",
239 ifmsh
->sync_offset_clockdrift_max
);
240 ifmsh
->sync_offset_clockdrift_max
= 0;
242 spin_unlock_bh(&ifmsh
->sync_offset_lock
);
245 static const u8
*mesh_get_vendor_oui(struct ieee80211_sub_if_data
*sdata
)
247 struct ieee80211_if_mesh
*ifmsh
= &sdata
->u
.mesh
;
250 if (!ifmsh
->ie
|| !ifmsh
->ie_len
)
253 offset
= ieee80211_ie_split_vendor(ifmsh
->ie
,
259 return ifmsh
->ie
+ offset
+ 2;
262 static void mesh_sync_vendor_rx_bcn_presp(struct ieee80211_sub_if_data
*sdata
,
264 struct ieee80211_mgmt
*mgmt
,
265 struct ieee802_11_elems
*elems
,
266 struct ieee80211_rx_status
*rx_status
)
270 WARN_ON(sdata
->u
.mesh
.mesh_sp_id
!= IEEE80211_SYNC_METHOD_VENDOR
);
271 msync_dbg("called mesh_sync_vendor_rx_bcn_presp");
272 oui
= mesh_get_vendor_oui(sdata
);
273 /* here you would implement the vendor offset tracking for this oui */
276 static void mesh_sync_vendor_adjust_tbtt(struct ieee80211_sub_if_data
*sdata
)
280 WARN_ON(sdata
->u
.mesh
.mesh_sp_id
!= IEEE80211_SYNC_METHOD_VENDOR
);
281 msync_dbg("called mesh_sync_vendor_adjust_tbtt");
282 oui
= mesh_get_vendor_oui(sdata
);
283 /* here you would implement the vendor tsf adjustment for this oui */
286 /* global variable */
287 static struct sync_method sync_methods
[] = {
289 .method
= IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET
,
291 .rx_bcn_presp
= &mesh_sync_offset_rx_bcn_presp
,
292 .adjust_tbtt
= &mesh_sync_offset_adjust_tbtt
,
296 .method
= IEEE80211_SYNC_METHOD_VENDOR
,
298 .rx_bcn_presp
= &mesh_sync_vendor_rx_bcn_presp
,
299 .adjust_tbtt
= &mesh_sync_vendor_adjust_tbtt
,
304 struct ieee80211_mesh_sync_ops
*ieee80211_mesh_sync_ops_get(u8 method
)
306 struct ieee80211_mesh_sync_ops
*ops
= NULL
;
309 for (i
= 0 ; i
< ARRAY_SIZE(sync_methods
); ++i
) {
310 if (sync_methods
[i
].method
== method
) {
311 ops
= &sync_methods
[i
].ops
;